ESR1 and breast cancer: At present, anti-hormone therapy is often used in breast cancer patients with ER\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$\alpha$$\end{document}α expression, which regulates the level of estrogen in the body by regulating the activity of estrogen receptors.